Coronal mass ejections (CMEs) are often associated with
erupted magnetic fields or disappeared chromospheric
filaments. The majority of CMEs headed directly toward the
earth (halo CMEs) are observed at 1AU as magnetic clouds
(MC). The 3D structure of a MC can be represented by a
force-free flux rope. When CMEs reach the earth, they may or
may not cause magnetic storms. The geoeffectiveness of CMEs
depends on the orientation of the magnetic field in them.

In our previous study we showed that the direction of the
axial field in a MC and its helicity are consistent with the
direction of the axial field and helicity of the erupted
filaments. We also suggested that geoeffectiveness of a CME
can be forecasted by using daily Big Bear Solar Observatory
full disk H\alpha and SOHO EIT 195Å~ images and SOHO/MDI
magnetograms, as well.

Here we continue to study the orientation of magnetic fields
in CMEs and its correlation with the occurrence of
geomagnetic storms. The study includes 11 earth directed
CMEs for which photospheric sources were reliably defined.
Our results further demonstrate that the geoeffectiveness of
a CME can be predicted by considering the orientation of the
CME's magnetic fields.

This work was supported in part by ATM-0076602, ATM-9903515
and NASA (NAG5-9682) grants. SOHO is a project of
international cooperation between ESA and NASA.

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